The Difference between Hot Rolling and Cold Rolling of Spiral Pipe

There are differences in the implementation of hot rolling and cold rolling of spiral pipes. Both processes are used to form steel sections or plates and have a significant impact on the structure and properties of the steel. Typically, the rolling of steel is dominated by hot rolling, while cold rolling is mainly used for the production of fine-type sections and thin plates.

During hot rolling, the casting organisation of the ingot can be destroyed, grain refinement can take place and microstructural defects can be eliminated, resulting in a dense steel structure and improved mechanical properties. This improvement is mainly reflected in the direction along the rolling direction, making the steel to a certain extent non-isotropic; at the same time, under high temperature and pressure, the casting of bubbles, cracks and loose parts can be welded together.

Cold rolling is at room temperature, through cold drawing, cold bending, cold drawing and other cold processing of steel plate or strip into various forms of steel, this process is fast and high yield, will not damage the coating, can produce a variety of cross-sectional form to meet the needs of different conditions of use; in addition, cold rolling can also make the steel to produce significant plastic deformation, thereby enhancing the yield point of steel.

The main difference between hot and cold rolling is that cold rolled steel allows local buckling of the cross-section to take full advantage of its subsequent load-bearing capacity; in contrast, hot rolled sections do not allow local buckling of the cross-section. In addition, the two produce residual stresses for different reasons, so the distribution of the cross-section there are also large differences; cold-formed thin-walled steel section residual stresses appear to be bending type, while the residual stress distribution of hot-rolled or welded steel sections is film type.

Finally, hot-rolled sections in the free torsional stiffness is better than cold-rolled sections, so the torsional performance of hot-rolled sections is better than the spiral pipe cold-rolled sections.

In conclusion, understanding the variations between hot rolling and cold rolling of spiral pipes is crucial for selecting the most suitable production method based on specific project requirements and performance expectations.